1. Technical Field of the Invention
The present invention relates to a telecommunications system and, in particular, to the establishment of an A-interface within a mobile telecommunications network.
2. Description of Related Art
With the development of Public Land Mobile Network (PLMN) telecommunications systems, mobile subscribers are able to freely travel within a particular country and utilize their mobile services Even if the mobile subscriber is roaming within a visited PLMN, the home PLMN associated with the roaming mobile subscriber keeps track of the current location of the mobile subscriber and accordingly makes the necessary arrangements and signaling communications to enable the mobile subscriber to receive and originate calls via another PLMN.
With the globalization of telecommunications networks and related human activities, more advanced mobile communications systems geographically encompassing the whole world are being developed. Such a system enables a mobile subscriber to roam not only within a particular continent or country, but throughout the world. One such system is the Personal Communications System (PCS). Another such system is a satellite based mobile communications system providing global coverage via satellite communications.
For both systems, a number of mobile switching centers (MSC) are strategically placed throughout the world to provide mobile service to a mobile subscriber anywhere in the world. Each MSC is, in turn, associated with one or more base station subsystems (BSS) for providing a radio connection with a mobile station traveling within the MSC coverage area. Once a BSS providing coverage for a particular geographic area detects or receives data from a mobile station, the data is automatically forwarded to the connected MSC. Applications within the MSC then analyze the received data and accordingly route the data to its intended destination. As a result of this application layer processing, a communications link known as an "A-interface" is effectuated between the serving BSS and its associated MSC. The A-interface in effect provides physical connection between a BSS and its assigned MSC and dictates that the serving BSS communicate with only one particular MSC. The connected MSC then identifies the received data from the BSS and processes the data to provide mobile service to the roaming mobile station.
Statistically, even when a mobile subscriber is traveling within a foreign country or continent, the majority of the call connections are made to or received from a single geographic location. For example, even when an American mobile subscriber travels to Europe, it has been shown that the majority of calls are made to or received from the United States. However, because the serving BSS is able to only communicate with its associated European MSC, whenever the mobile station roaming within Europe transmits data to the serving BSS, applications within the connected European MSC receives the data, identifies the received data by utilizing the subscriber information copied from the home location register (HLR) associated with the mobile station, and reroutes the data to the American PSTN upon determining that the calls are destined for America. However, such an implementation requires the applications within the visited MSC to always communicate with the HLR associated with the mobile station to retrieve the requisite subscriber information, to perform location update with that HLR, and to always identity and process the data, i.e., calls, even though the majority of calls are destined towards a different PSTN. It may further result in unoptimized use of speech circuits within the connecting telecommunications networks.
Accordingly, it would be advantageous for the European BSS to instead communicate all received data directly with the American MSC associated with the roaming mobile station. As a result, there is a need for a mechanism to break the A-interface that exists, for example, between the European BSS and the application modules within the European MSC, and to enable the European BSS to dynamically establish an A-interface connection with application modules of any other MSC associated with a particular mobile station.